With the widespread and ever increasing use of all types of electrical equipment, there has developed a need for an apparatus which can control the unauthorized use of this equipment. The need for this type of apparatus has developed as a result of the increasing interest in and emphasis on security and safety, as related to the operation of electrical equipment.
In the field of power tools which are used in the home and in schools, there is a need to restrict the use of these devices to authorized users and prevent use thereof by small children in the home or students who have not received the appropriate training. There is a similar need to limit the use of certain electrical kitchen equipment such as grinders, food processors and slicers.
In the home, it is often necessary to control the use of television receivers and video tape recorders by children. This need is related to a desire to limit the extent of television viewing by children and to restrict this use to programming which is considered appropriate.
In commercial offices, there is often a need to restrict the use of office copiers, typewriters, and other electrical equipment and to prevent the use of this equipment by unauthorized persons. This requirement often occurs when an office must remain open for purposes of cleaning or maintenance after the end of the normal business day when the authorized personnel are no longer present.
Another reason for the development of a means of limiting the operation of equipment to authorized users has been the widespread application of computers to every phase of commercial and industrial activity. This has resulted in a situation where an unauthorized user can, either unintentionally or intentionally as a result of malice, do a substantial amount of damage. This damage can result from both the entry into computer networks and the destruction or tampering with the equipment or data, as well as the obtaining of sensitive information stored in these files.
In addition, in laboratories where certain electrically operated sensitive test equipment is located, there is a similar need to restrict access to such equipment.
Recently, selected types of electrical equipment include a keylock feature in which a removable key is used to activate a switch which applies electrical power to the equipment. This feature meets the need for a means for limiting the operation of the equipment to authorized users. However, this feature is found only in relatively expensive types of equipment. The incorporation of this feature on existing equipment is quite costly and in most cases extremely difficult or impossible. Thus, there is compelling need for a practical and economical means for controlling the use of electrical equipment.